1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device using a salicide process in which silicide is formed simultaneously on a gate and source/drain regions.
2. Description of the Related Art
In a conventional method for manufacturing a semiconductor device having a size of less than 1.2 μm, silicide is formed on a polysilicon substrate using tungsten, and is used as a gate electrode of a metal oxide semiconductor field effect transistor (MOSFET). However, as semiconductor devices become increasingly high-integrated to have a size less then 0.35 μm, various methods for forming electrodes using titanium in MOS transistors are widely used.
FIGS. 1A to 1D are sectional views illustrating a conventional method for manufacturing a semiconductor device.
As shown in FIG. 1A, a field oxidation film 110 for insulating unit complementary metal oxide semiconductor field effect transistors (CMOSFETs) from each other is formed on a silicon substrate 100.
Thereafter, as shown in FIG. 1B, a gate oxidation film 140 for forming a gate is grown on the silicon substrate 100. Then, a polysilicon gate is formed by stacking a polysilicon film 150 doped with impurities serving as an electrode of the gate on the gate oxidation film 140 and forming a pattern using a mask.
As shown in FIG. 1C, source/drain junctions 170 are formed by injecting impurities two to four times into regions used as source and drains of a transistor using a spacer oxidation films 160 interposed between.
Thereafter, a blank oxidation film 180 is formed on the field oxidation film 110, and is removed from places other than regions, in which silicide is not formed, by etching.
Then, a silicide film 190 is formed by a salicide process.
In the conventional method for forming silicide using the conventional technique, since a process margin does not exist when the etching of the spacer oxidation film or the blank oxidation film is performed during the formation of the source and drains, the silicide film is formed or remains through the side wall of the transistor even by a small error in the process, thereby generating short between a gate and the drains or between the gate and the source, or increasing parasitic capacitor, thus exerting a negative influence upon yield and characteristics of products.
Accordingly, a method for manufacturing a semiconductor device, in which a process margin for etching is assured to solve various problems generated from the formation of silicide, has been increasingly required.